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LM324 with two 555 timer ICs

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555

You need to make your schematic correct so we can tell which resistor is r1 and which is r2 for the calculator. Make your schematic look like the one in the picture and recalculate. I think you want the duty cycle to be close to 50% for best results.
35 to 40 KHZ is ok.
Maybe your circuit is different than your schematic?
 

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You need to make your schematic correct so we can tell which resistor is r1 and which is r2 for the calculator. Make your schematic look like the one in the picture and recalculate. I think you want the duty cycle to be close to 50% for best results.
35 to 40 KHZ is ok.
Maybe your circuit is different than your schematic?

Oh! I didn't saw that my circuit is wrong. Thank you I'll change it again.

Edit: Here it is.

:( My bad, I rushed etching and soldering the first design without having a thorough check.

What is the allowable frequency for the 1st timer? and I'm hearing always the word duty cycle. I still don't get the purpose of duty cycle after some search. I have seen 60% on some of the designs.
 

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I soldered the sensor design on my 2nd PCB and so far so good. I just hope I wont encounter any problem when I connect it to the 1st PCB where LM324 and Microcontroller are placed. Thanks a lot ronv. :D
 
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sensor

Usually duty cycle is defined as the time a pulse is positive divided by the time for 1 cycle. So the duty cycle for your second timer is over 90%. (Picture 1)The sensor would like it better if it were closer to 50%. You can do this by switching R3 & R4. (see picture 2). The timing for the first timer would be a little better if R2 were a little bigger - say 1.5k. Some of the sensors like more time in between pulses. The duty cycle on the first timer is OK. As a matter of fact it needs to be the way it is for your circuit to work.
Where are you located? I see the times on your posts and wonder if you ever sleep. :+)
 

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lol I'm from Philippines and I'm still going to school around 6-8 hrs a day. My apologies about the lengthy post time gaps.

One more thing, does the duty cycle also affects the range of the emitter since 50% looks better than 90%? Like if its exactly 50% on the 2nd 555 Timer circuit's duty cycle, would it extend the range of the sensors like for example the remote control of a television?

Okay, if I'll encounter problems I'll just desolder the resistors and make some changes :D THANKS
 
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Cool, I spent a bit of time in the Philippines with a company called Sunward (later Read-Rite) making disk drive heads.
 
I don't know how much difference the 50% duty cycle would make, but I think some. Besides it is the same resistors just switching places.
 
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